If you wish the transaction to go through, why refuse it?
If you wish to declare your intent to be upon lawful money, then add your demand to the agreement. It is ALL Bullsh$t, your signature creates money??? If that is how the system works, fine; however, i will be novating the contract significantly.
If you do not wish the transaction to go through but wish to learn more about the process, ask to speak with the "big cheese" at the bank because you have some questions that only he may know the answer to. You will probably be asked to leave.
At the closing table, gather all the papers together before you sign and inform the "witness" (attorney, notary, title agent, etc.) that you will let them know when you are done. Novate the contract according to the terms you wish. Keep the originals (have them notarized) and hand the witness the copies. One must know how to handle the breach which will most likely incur when one does this (do you think the bank will perform under the new terms?).
Notice how your signature is the only one on the mortgage closing "contract" (besides witness). When you begin "paying" the contract becomes valid because you believe it is as evidenced by your actions. Otherwise, a valid contract requires BOTH parties to sign.